Date on Master's Thesis/Doctoral Dissertation

Document Type

Degree Name

Department

Degree Program

Committee Chair

Committee Co-Chair (if applicable)

Committee Member

Alexander, James E.

Committee Member

Cobbs, Gary

Committee Member

Page, Robert B.

Committee Member

Yanoviak, Stephen P.

Author's Keywords

conservation; arthropod; biodiversity; urban

Abstract

Although urbanization is a leading cause of species extinction throughout the world, the impact of urban development on arthropods is little studied and, as a result, poorly understood. I used three distinct approaches to studying arthropod conservation in North America. First, I used landscape genetics techniques to study the impact of urbanization on gene flow among populations of Rabidosa rabida, the rabid wolf spider. While gene flow was not detrimentally reduced, urban development correlated with a reduction in migration rates among populations, and to my knowledge, this is the first study to document isolation by resistance in spiders. Next, I examined how lentic and lotic odonate communities within the same landscape were affected by urbanization. Due to the inherent differences between lentic and lotic ecosystems and between dragonflies and damselflies, different environmental factors contributed to the persistence of particular species and thus to the makeup of adult odonate communities in urban areas. The different responses of dragonflies, damselflies, and spiders to urban development suggested that dispersal abilities strongly predict resilience to altered landscapes. Finally, I identified ecological correlates of an extinction risk assessment for North American odonates. Two of those correlates, geographic range size and length of flight period, are surrogate measures of dispersal. Both dragonfly and damselfly extinction risk assessments correlated with these two traits, but dragonfly assessments also correlated with the interactions between length of flight period and both geographic range size and habitat breadth. Collectively, this research showed that not all arthropods are negatively affected by urban development and that even closely related taxa are not always similarly affected. These differing responses were likely due to interspecific differences in dispersal abilities and life-history patterns, and possibly in odonates to taxonomic differences in flight capability and voltinism. These results highlight the need for further research on identifying the mechanisms driving urban biodiversity patterns and gaining a better understanding of the basic ecology of invertebrates.